The present invention relates to a method and an apparatus for generating electron channeling patterns, and more particularly to a method and an apparatus for generating the electron channeling patterns in the relation to a scanned image formed by electrons emitted from a sample.
A sample is scanned by a converged electron beam while a screen of a cathode-ray tube is scanned by a cathode-ray beam (electron beam) in synchronism with the scanning of the sample by the converged electron beam and the intensity modulation of the cathode-ray tube is made by secondary electrons or a reflected electron signal emitted from the sample so that a secondary electron image or a reflected electron image in a scanned area of the sample (hereinafter simply referred to as a sample scanned image) is displayed on the screen of the cathode-ray tube.
On the other hand, when a mode is changed from a display mode of the sample scanned image to an electron channeling mode, the electron beam irradiating the sample is collimated and the collimated electron beam is angularly scanned about a certain position of the sample. In other words, an incident angle and an orientation angle of the collimated beam in respect to a certain position of the sample is scanned. Thus, the secondary electrons or the reflected electrons emitted from the sample are introduced into the cathode-ray tube for the intensity modulation so that the electron channeling patterns are displayed on the screen of the cathode-ray tube instead of the sample scanned image. The electron channeling patterns are used to analyze the crystallographic orientation of crystal material (refer to "The Generation And Application Of SEM Electron Channeling Patterns" by E. M. Schulson, et al. J. Materials Sci. 6, 213-217 (1971)).
Generally, a sample scanned image is generated with a proper magnification and a desired location of the sample scanned image from which electron channeling patterns are desired to be obtained is selected. Then, the sample is moved to position the selected location to an irradiation position of the electron beam. The electron channeling pattern image generated in such a condition is recorded as a photograph or stored in a memory. When there are a plurality of locations from which the electron channeling patterns are desired to be obtained, the same steps are repeated plural times.
For example, when the crystallographic orientation of steel plate is analyzed by the electron channeling patterns to estimate the steel plate, it is necessary to obtain the electron channeling patterns for several tens to several hundreds grains confirmed through observation of the sample scanned image. In this case, the efficiency of positioning of the grains by the above-described conventional method is extremely deteriorated and accordingly it is substantially impossible to estimate exactly the sample by means of the electron channeling patterns.